The present invention relates to a conveyor system as well as a method for avoiding collisions between transport units, or conveyed goods, at intersection points of conveyor lines, for example, if they cross each other in the intersection point or converge to a single conveyor line.
Conveyor-line switches and crossings are known in the prior art, where the conveyed goods are stopped, if a collision with conveyed goods of another conveyor line is approaching. Typically, the stop of the conveyed goods is conducted by an abrupt deceleration. Then, the conveyed goods are accelerated again as soon as the other conveyed goods have passed the intersection point.
The document WO 97/09256 discloses a method and apparatus for injecting piece-good parts on a removal conveyor. The piece-good parts are transported to the removal conveyor by means of a delivery conveyor. The delivery conveyor includes at least one buffer belt, a request belt and an injection belt. The buffer belt, the request belt and the injection belt can be operated at different velocities. The removal belt is operated at a constant velocity. Thus, it is possible that piece-good parts are directed from the delivery conveyor to predetermined target locations on the removal conveyor.
The document DE 10 2004 035 821 discloses a method and an apparatus for dynamically optimizing gaps. The method serves to reduce and unify distances between piece goods which are conveyed, for example, on transportation belts. In this manner, the density can be optimized. Also, an increase of the utilization of the conveyor is possible.
The document EP 1 228 986 A1 also discloses a method and an apparatus for optimizing gaps on a conveyor belt.
The deceleration as well as the acceleration requires relatively much power, i.e. such systems do not work in a power-efficient manner. Further, a relatively high maintenance effort is required with such known systems, since the drives of the conveyor lines are heavily stressed by the steady deceleration and acceleration. Another disadvantage is to be seen in that the deceleration and acceleration are loud.